Soil acidification induced by reactive nitrogen (N) inputs is a major environmental issue in grasslands, as it lowers the acid neutralizing capacity (ANC). The specific impacts of different N ...compound forms on ANC remain unclear. Grassland management practices like mowing and grazing can remove a considerable amount of soil N and other nutrients, potentially mitigating soil acidification by removing N from the ecosystem or aggravating it by removing base cations. However, empirical evidence regarding the joint effects of adding different forms of N compounds and mowing on ANC changes in different-sized soil aggregates is still lacking. This study aimed to address this knowledge gap by examining the effects of three N compounds (urea, ammonium nitrate, and ammonium sulfate) combined with mowing (mown vs. unmown) on soil ANC in different soil aggregate sizes (>2000 μm, 250–2000 μm, and <250 μm) through a 6-year field experiment in Inner Mongolia grasslands. We found that the average decline in soil ANC caused by ammonium sulfate (AS) addition (−78.9%) was much greater than that by urea (−25.0%) and ammonium nitrate (AN) (−52.1%) as compared to control. This decline was attributed to increased proton (H+) release from nitrification and the leaching of exchangeable Ca2+ and Mg2+. Mowing aggravated the adverse effects of urea and AN on ANC, primarily due to the reduction in soil organic matter (SOM) contents and the removal of exchangeable Ca2+, K+, and Na + via plant biomass harvest. This pattern was consistent across all aggregate fractions. The lack of variation in soil ANC among different soil aggregate fractions is likely due to the contrasting trend in the distribution of exchangeable Ca2+ and Mg2+. Specifically, the concentration of exchangeable Ca2+ increased with increasing aggregate size, while the opposite was true for that of exchangeable Mg2+. These findings underscore the importance of considering the forms of N compounds when assessing the declines of ANC induced by N inputs, which also calls for an urgent need to reduce N emissions to ensure the sustainable development of the meadow ecosystems.
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•(NH4)2SO4 addition caused greater decline in ANC than CO(NH2)2 or NH4NO3 addition.•Greater ANC decline was associated with greater NH4+ inputs, Ca2+ and Mg2+ loss.•Mowing aggravated the effect of CO(NH2)2 or NH4NO3 by reducing SOM and base cations.•Aggregate size had no significant effect on ANC.
The microbiome of grassland soils provides ecosystem services essential to plant health and productivity, including nutrient cycling and suppression of soil-borne diseases. Understanding how soil ...management practices affect soil microbial communities will provide opportunities by which indigenous soil microbes and their functions can be managed to sustain or promote plant growth and enhance disease suppressiveness. Here, we investigated the impact of 20 years of plant residue management in a long-term grassland field trial on soil chemical and (micro)biological properties, in particular the suppression of damping-off disease of kale caused by the fungal root pathogen Rhizoctonia solani AG 2–1. Plant residue management led to significant variation in the community structure of the bacterial genus Pseudomonas between treatments. Soil organic matter quality (inferred carbon recalcitrance) was responsible for 80% of the observed variation in Pseudomonas community structure. Furthermore, increased Pseudomonas species diversity (Shannon's index), microbial activity, soil organic matter content, and carbon availability distinguished suppressive (low disease) soils from conducive (high disease) soils. More specifically, Pseudomonas species diversity and richness (Margalef's) were identified as the primary parameters explaining the greatest proportion (>30%) of variation in the disease suppressive capacity of soils across treatments. Collectively, our results suggest that management-induced shifts in Pseudomonas community composition, notably species diversity and richness, provide a better indicator of disease conduciveness for a broad-host range fungal pathogen than soil chemical parameters. In conclusion, our study indicates that frequent addition of organic residues to agricultural grassland soils enhances the diversity and activity of plant-beneficial bacterial taxa.
•Plant residue management led to variation in Pseudomonas bacterial community structure.•Soil OM quality explained 80% of the variation in Pseudomonas community structure.•Pseudomonas species diversity explained >30% of variation in soil suppressiveness.•Increased Pseudomonas species diversity distinguished suppressive from conducive soils.•Increased carbon availability distinguished suppressive from conducive soils.
Grassland management is one of the most important means to address grassland degradation on the Qinghai-Tibet Plateau, but at present, the primary goal is still to improve grassland productivity, and ...little research has been conducted on grassland management based on its ecosystem service relationships. Based on remote sensing and meteorological data, we calculated and analyzed the spatial and temporal changes, trade-offs and synergistic relationships between livestock production and water retention services in alpine grassland on the southern slopes of the Qilian Mountains (SSQM), and designed a grazing management plan for sustainable development in the region. The results showed that the value of livestock production and water retention services of alpine grassland decreased from east to west, and their relationship is dominated by synergy and complemented by trade-offs. The synergistic relationships are concentrated in the Qinghai Lake Basin in the south and the river valleys in the north, while the trade-offs are scattered in the steeper terrain in the western and eastern parts of the study area. The scenario of preserving all water retention services and losing some livestock production services is sustainable. Based on this scenario we divided the alpine grassland of the study area into maintenance grazing, rotational grazing and grazing exclusion of 65.8%, 32.0% and 2.2%, respectively. Our study demonstrates that ecosystem service relationships have the potential to guide grassland management, and the results will provide new approaches to alpine grassland management.
•We design alpine grassland management based on ecosystem service relationships.•Grassland management scenarios based on different preferences are compared.•Grazing strategies that can mitigate conflicts over ecosystem services are proposed.
Land-use change is a major driver of biodiversity loss worldwide. Although biodiversity often shows a delayed response to land-use change, previous studies have typically focused on a narrow range of ...current landscape factors and have largely ignored the role of land-use history in shaping plant and animal communities and their functional characteristics. Here, we used a unique database of 220,000 land-use records to investigate how 20-y of land-use changes have affected functional diversity across multiple trophic groups (primary producers, mutualists, herbivores, invertebrate predators, and vertebrate predators) in 75 grassland fields with a broad range of land-use histories. The effects of land-use history on multitrophic trait diversity were as strong as other drivers known to impact biodiversity, e.g., grassland management and current landscape composition. The diversity of animal mobility and resource-acquisition traits was lower in landscapes where much of the land had been historically converted from grassland to crop. In contrast, functional biodiversity was higher in landscapes containing old permanent grasslands, most likely because they offer a stable and high-quality habitat refuge for species with low mobility and specialized feeding niches. Our study shows that grassland-to-crop conversion has long-lasting impacts on the functional biodiversity of agricultural ecosystems. Accordingly, land-use legacy effects must be considered in conservation programs aiming to protect agricultural biodiversity. In particular, the retention of permanent grassland sanctuaries within intensive landscapes may offset ecological debts.
Romanian grasslands have high nature value, being among the most important biodiversity hotspots at the European level. The European Union Common Agricultural Policy (CAP) contradicts the ...Biodiversity Strategy to 2020 objectives by hindering coordinated grassland governance and collaboration among the involved actors. At the European level, few attempts have been made in creating conceptual strategies for implementing conservation measures in a multi-actor and multi-scale governance setting. Our paper focuses on a comparative network analysis of grassland governance of three Romanian regions (Iron Gates Natural Park – SW; Sighisoara - Tarnava Mare – center; and Dobrogea - SE), representatives for grassland management in mountain and lowland landscapes. We investigated the structural characteristics of one-mode directed governance networks in the three protected areas (standard cohesion and reciprocity metrics, exponential random graph models), the position of actors participating in networks (node-level centrality metrics), and the perception of CAP influence on grassland governance by farmers benefiting of CAP agri-environmental payments. In Sighisoara, grassland governance has been centralized but biodiversity-friendly, while in Iron Gates, grasslands were traditionally managed through a decentralized, community-level system, and this type of governance continues to date. In Dobrogea, grassland governance was performed in an intensive, centralized state-run management regime during the communist time and by large landowners after the transition period ended. Our findings illustrate the structure of the three governance networks and dissimilar patterns of collaboration, indicating distinct particularities to be considered when exploring barriers to and options for successful governance in traditionally managed grasslands in the context of CAP measures-driven management.
•We explored governance networks around the management of grasslands of Romania.•We used network analyses and semi-structured interviews.•CAP and protected area regulations failed to reverse the threats to traditionally managed grasslands.•In areas with a liberal past governance networks are centralized around public bodies.
Grassland systems frequently exhibit small‐scale botanical and structural heterogeneity with pronounced spatio‐temporal dynamics. These features present particular challenges for sensor applications, ...in addition to limitations posed by the high cost and low spatial resolution of many available remote‐sensing (RS) systems. There has been little commercial application of RS for practical grassland farming. This article considers the developments in sensor performance, data analysis and modelling over recent decades, identifies significant advances in RS for grassland research and practice and reviews the most important sensor types and corresponding findings in research. Beside improvements of single sensor types, the development of systems with complementary sensors is seen as a very promising research area, and one that will help to overcome the limitations of single sensors and provide better information about grassland composition, yield and quality. From an agronomic point of view, thematic maps of farm fields are suggested as the central outcome of RS and data analysis. These maps could represent the relevant grassland features and constitute the basis for various farm management decisions at strategic, tactical and operational levels. The overarching goal will be to generate low cost, appropriate and timely information that can be provided to farmers to support their decision‐making.
There is a global requirement to improve the environmental sustainability of intensively managed grassland monocultures that rely on high rates of nitrogen fertiliser, which is associated with ...negative environmental impacts. Multi‐species grass–legume mixtures are a promising tool for stimulating both productivity and sustainability in intensively managed grasslands, but questions remain about the benefit of increasing the diversity of plant functional groups.
We established a plot‐scale experiment that manipulated the diversity of plant communities from a six‐species pool comprising three functional groups: grasses, legumes and herbs (two species each). Communities were grown as monocultures, or mixtures of two to six species, following a simplex design. This allowed us to quantify species’ identity effects and functional group interaction effects. To investigate the impact of severe weather events, main plots were split and two levels of water supply, ‘rainfed’ and a 2‐month experimental drought, were applied. Mineral nitrogen fertiliser was applied at 150 kg ha−1 year−1, and a Lolium perenne monoculture received 300 kg ha−1 year−1 (300N) as a highly fertilised comparison. Annual above‐ground biomass was measured for 2 years.
We found a strong positive effect on yield due to functional group interactions. Multi‐species communities with three functional groups yielded more than the best‐performing monoculture over a large range of different relative abundances of the three functional groups. The highest diversity community outperformed the 300N L. perenne under rainfed conditions.
Although species' monoculture yields were generally reduced by the experimental drought, the interaction effects were not affected by drought and remained sufficiently large for the six‐species mixture under drought to have similar yields to both the best‐performing monoculture and the 300N L. perenne under rainfed conditions.
Synthesis and applications. Plant diversity can result in higher yields, mitigate the yield risks associated with extreme weather events and displace fertiliser inputs and their embedded greenhouse gas emissions. Multi‐species swards offer a practical, farm‐scale management action to enhance the sustainability of intensive grassland production.
Plant diversity can result in higher yields, mitigate the yield risks associated with extreme weather events and displace fertiliser inputs and their embedded greenhouse gas emissions. Multi‐species swards offer a practical, farm‐scale management action to enhance the sustainability of intensive grassland production.
Alpine grasslands are essential for carbon sequestration and food supply for domestic and wild herbivores inhabiting mountainous areas worldwide. These biomes, however, are alternatively threatened ...by the abandonment of agricultural and livestock practices leading to a fast-growing shrubification process while other mountain grasslands are suffering from the impacts of overgrazing. The functioning of alpine meadow ecosystems is primarily driven by climatic conditions, land-use legacies and grazing. However, although it is critically important, the role of large herbivores on the aboveground biomass and protein content of palatable plants is poorly understood for most alpine meadows. In this work, we explore the effects of grazing on grassland vegetation at two different spatial and temporal scales in the Eastern Pyrenees, Spain. Remote sensing was used to assess the effect of high and moderate grazing (HG and MG respectively) on grass biomass using the leaf area index (LAI) at the meso-scale (patches between 2.3 and 38.7 ha). We also explored the impact of null (NG), overgrazing (MO, mimicked overgrazing) and high (HG) grazing intensities at local scale setting eighteen 1 m2 exclusion boxes in six meadows (three boxes each) commonly used by domestic and wild ungulates. Historical satellite data showed that LAI values are greater in high than in low grazed areas (HG, mean = 0.66, LG, mean = 0.55). Along the same lines, high and moderate grazing pressures improved biomass production at the local-scale (HG, mean = 590.3 g/m2, MO, mean = 389.3 g/m2 and NG, mean = 110.8 g/m2). Crude protein content reached higher values under MO pressure than under HG pressure. Our results confirm that grazing intensity exerts significant changes on the above-ground biomass production and the protein content of plants consumed by domestic (cattle and horses) and wild ungulates (Southern Chamois, Rupicapra pyrenaica). We can conclude that ungulates sustain biomass and nutritive values of grass exerting a negligible effect on biomass and protein content of woody vegetation. Our results will inform management guidelines to support profitable grazing activities and promote conservation of the open landscapes in the alpine ecosystems under the current global change scenario.
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•We quantified the impact of grazing on biomass production and nutritional value of meadows.•Moderate grazing increases biomass production and protein content of grass.•Biomass and protein contents of woody plants was not affected by grazing.•High grazing reduces biomass production but increases protein content of grass.•Grazing management is important to keep the nutritional value of alpine meadows.
Ecosystem productivity usually exhibits first increase and then saturated response to increasing nitrogen (N) additions, yet the broad‐scale pattern and potential drivers of the N saturation ...threshold are little investigated.
By synthesizing N addition experiments with at least four N‐input levels from the global grasslands, we applied the quadratic‐plus‐plateau model to fit the above‐ground net primary productivity (ANPP)–N rate relationship, and estimated the saturation threshold for N rate (critical N rate, NCR) and ANPP (maximum ANPP, ANPPmax) from the inflection point where ANPP no longer statistically increased with N rate for individual experiments. Based on these estimations, we investigated the spatial pattern and driving factors of NCR and ANPPmax.
The mean NCR and ANPPmax were 15.0 and 477.0 g m−2 year−1, respectively, but varied substantially among single‐site experiments. Management strategies (e.g. biomass harvest, different N forms and addition frequencies) minimally influenced both parameters. Structural equation models demonstrated that the spatial differences in NCR and ANPPmax were mainly explained by aridity index, and soil carbon (C)/N ratio also predicted the variation in NCR.
Given that grasslands are important not only for the trend and variability of the land C sink but also for the maintenance of pasture yield, the pattern and controls of NCR and ANPPmax, as revealed by the current study, are crucial for constructing robust predictions of C sink capacity and improving N fertilizer management in grasslands.
中文摘要
工业革命以来, 陆地生态系统氮输入强度显著增加。氮有效性增加能够提高生态系统生产力, 然而, 随着氮输入量的不断增加, 生产力的促进效应逐渐减弱, 最后达到饱和。估算生产力从线性增加转变至平台期的拐点, 即氮饱和阈值, 是全球变化领域的重要问题之一。尽管如此, 学术界还不清楚氮饱和阈值的大尺度格局及其调控因素。
本研究搜集了全球55个草地氮添加控制实验(四个以上氮水平), 利用二次加平台模型拟合地上净初级生产力与施氮量的关系, 通过高斯‐牛顿迭代法估算氮饱和阈值的两个相关参数: 临界施氮量和最大生产力。在此基础上, 解析了二者的空间格局及其调控因素。
研究发现: 全球尺度上, 临界施氮量和最大生产力在不同个体研究中变异较大, 平均值分别为15.0和477.0 g m−2 year‐1。结构方程模型分析发现, 干旱指数是解释两个参数空间变异的主要因素；另外, 土壤碳氮比也能够影响临界施氮量的大尺度格局。
草地生态系统不仅具有重要的碳汇功能, 而且也是畜牧业的重要基地。因此, 本研究揭示的氮饱和阈值的大尺度格局及其调控因素, 能够为准确预测全球变化背景下草地碳汇强度提供基准, 也为优化草地氮素管理提供理论支撑。
A free Plain Language Summary can be found within the Supporting Information of this article.
A free Plain Language Summary can be found within the Supporting Information of this article.
The research gap between rangeland/livestock science and conservation biology/vegetation ecology has led to a lack of evidence needed for grazing‐related conservation management. Connecting ...scientific understanding with traditional ecological knowledge of local livestock keepers could help bridge this research and knowledge gap.
We studied the grazing behaviour (plant selection and avoidance) of beef cattle (c. 33,000 bites) on species‐rich lowland pastures in Central Europe and traditional herding practices. We also did >450 outdoor interviews with traditional herders about livestock behaviour, herders' decisions to modify grazing behaviour and effects of modified grazing on pasture vegetation.
We found that cattle grazing on species‐rich pastures displayed at least 10 different behavioural elements as they encountered 117 forage species from highly desired to rejected. The small discrimination error suggests that cattle recognize all listed plants ‘by species’.
We also found that herders had broad knowledge of grazing desire and they consciously aimed to modify desire by slowing, stopping or redirecting the herd. Modifications were aimed at increasing grazing intensity in less‐desired patches and decreasing grazing selectivity in heterogenous swards.
Synthesis and applications. The traditional herd management practices presented here have significant conservation benefits, such as avoiding under‐ and overgrazing, and targeted removal of pasture weeds, litter and encroaching bushes, tall competitive plants and invasive species. We argue that knowledge co‐production with traditional herders who belong to another knowledge system could help connect isolated scientific disciplines especially if ecologists and rangeland scientists work closely with traditional herders, co‐designing research projects and working together in data collection, analysis and interpretation. Stronger links between these disciplines could help develop evidence‐based, specific conservation management practices while herders could contribute with their practical experiences and with real‐world testing of new management techniques.
The traditional herd management practices, presented here, have significant conservation benefits, such as avoiding under‐ and overgrazing, and targeted removal of pasture weeds, litter and encroaching bushes, tall competitive plants and invasive species. We argue that knowledge co‐production with traditional herders who belong to another knowledge system could help connect isolated scientific disciplines especially if ecologists and rangeland scientists work closely with traditional herders, co‐designing research projects and working together in data collection, analysis and interpretation. Stronger links between these disciplines could help develop evidence‐based, specific conservation management practices while herders could contribute with their practical experiences and with real‐world testing of new management techniques.
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